Just finished the Dark Tower series. Review behind the cut, may or may not have spoilers (I wrote it without any at first but want to expand it).
A villain in Orwell's 1984 once said,: "If you want a vision of the future, imagine a boot stamping upon a human face - forever." If you want a vision of the slow, lingering ending of this series, imagine Stephen King giving you the finger and blowing a giant raspberry, while masturbating. Forever.
And yet, the parts that aren't awful are so awesome that it's still worth it.
Book 1: I didn't enjoy it that much, actually, but it was very short (almost a novella) and by the end I was attached to the main quest enough to want to continue the series, so it did its job. He published a "revised edition" later on, so maybe I'll read that one and see if I like it better.
Book 2: One of the stronger ones. Thrilling action, creepy monsters, and nifty magic.
Book 3: Dragged in places, but did a great job of expanding on the characters and setting, especially the larger mythos and history, which are very cool.
Book 4: Pulls in a whole extra set of heroes and villains that you know beforehand are only going to be around for this book and are not going to advance the main plot significantly, which for me leaves little incentive to care about them in a long series like this. I skimmed most of this one.
Book 5: My favorite; in fact I'd rate this as one of my all-time favorite sci-fi or fantasy books (the series is a blend). It dwells mostly on a "side quest" (I keep thinking of the plot in roleplaying terms) that only minimally advances the main quest, but it's in a fantastic side setting that's easy to love. Fascinating peeks into the organization of main villains, who are getting pretty cool. The final third or so of the book is marred by the first hints of the author's ego intruding on the story, but at this point the reader has no inkling of the creeping horrors to come (and not the nifty monster kinds).
Book 6: The plot flow and action were good in this one, but I didn't have many "whoa this is awesome" moments; it was worth reading rather than skimming, but only because it was part of the series and I wanted to get to the ending. Involves pages upon pages of pure author-ego. Those parts were actually fun to read, in the "can it get worse?...holy crap, yes it can" sort of way.
Book 7: The most extreme blend of high and low points. By then I'd invested so much reader-energy into the main character's final goal that it would have been thrilling no matter what happened. The beginning and middle had some great stuff interspersed with the most ego-tastic pieces of author ego yet, and at that point it had lost its snark value. Ending was both thrilling and disappointing.